By 2017, white supremacist groups embraced Mr. Camus’ ideas and added antisemitic conspiracy theories. They adopted a new slogan — “You will not replace us” — chanted at rallies, most infamously at the Unite the Right rally in Charlottesville, Va., that August, where a white nationalist killed a counterprotester. White supremacists who committed mass killings in Christchurch, New Zealand, and El Paso, Tex., in 2019 both referred to the theory in their respective manifestoes.
“These conspiracies are at the core of the Republican Party right now and I don’t think it’s partisan to say that,” said Amy Spitalnick, the executive director of Integrity First for America, which won a lawsuit against the organizers of the 2017 Charlottesville rally.
Representative Elise Stefanik of New York, who represents a district in Northern New York and who replaced Ms. Cheney last year as the No. 3 House Republican, ran an online ad last fall about how “amnesty” to the undocumented would “overthrow our current electorate.”
Her office put out a statement on Monday accusing the news media of “disgraceful, dishonest and dangerous” smears in linking her rhetoric to the Buffalo attack in any way.
“The shooting was an act of evil,” said her spokesman, Alex DeGrasse, who added in a statement about “illegals” that she “has never advocated for any racist position or made a racist statement.”
Senator John Thune of South Dakota, the No. 2 Senate Republican, said on Monday that “it’s unfortunate that there are sites out there where these people go and get these crazy ideas in their head and act on it.” When asked about his colleagues who have repeated elements of replacement theory, he added: “Nobody should be giving voice to or support in any way to some of these things.”
Reporting was contributed by Azi Paybarah, Karen Yourish, Jennifer Medina, Jazmine Ulloa and Charles Homans.